The present disclosure relates generally to electrical power equipment for example power conversion systems and more particularly to techniques for detecting degradation in multiphase power capacitors. Motor drives and other electric power conversion systems convert input power from a line-side source to a different form to provide controlled drive currents to the windings of an electric motor or other load, where the output frequency is variable. Variable Frequency Drives (VFDs) typically include a passive or active rectifier with AC input power being rectified to create DC link power in an intermediate DC circuit. The intermediate DC power is fed to an output inverter which creates a variable frequency single or multi-phase AC output driving a motor load at a controlled speed and torque. VFDs often include filter circuits at the power input and/or load output, including capacitors. Capacitor degradation or other fault conditions in the capacitors can adversely affect the power converter operation. Previous systems employed pressure relays to detect change in pressure inside the capacitor, but such techniques require extra components and increase the size, cost, and complexity of motor drives. Moreover, detecting degradation of a first degrading element is important for taking action prior to device failure. At the same time, however, it is desirable to avoid nuisance alarms associated with system voltage unbalance and/or system transient/harmonic conditions as opposed to actual capacitor degradation. In this regard, conventional techniques are not universally applicable in all system grounding configurations, and thus may work reliably in some systems and not in others. Thus, there is a need for improved apparatus and techniques by which the adverse effects of capacitor degradation can be avoided or mitigated by detecting degrading capacitor conditions without adding to the system size, cost and complexity.